Optical fiber light source with composite overcoating structure

ABSTRACT

A solid body made of an inactive, light transmissive material ( 3 ) has embedded therein an optical fiber ( 6 ) having a lengthwise segment ( 9 ) in which a scattering structure is formed that is to redirect primary propagating light sideways out of the fiber ( 6 ). An active photoluminescent layer integrated in the optical fiber ( 6 ) is to wavelength-convert the primary light into secondary light. The solid body is generally cylindrical but without rotational symmetry about the center longitudinal axis ( 2 ) of the fiber ( 6 ). A portion of the outer side surface of the body is curved and is covered by an external reflector ( 4 ), while another portion of the outer side surface is uncovered by the reflector in order for the secondary light to emerge. Other embodiments are also described and claimed.

This patent application claims the benefit of the earlier filing date ofU.S. Provisional Application Ser. No. 62/268,815 filed Dec. 17, 2015.

FIELD

An embodiment of the invention relates to a light source that has anoptical fiber based side-emitter embedded in a composite overcoatingstructure, where the latter is designed to modify the illuminationscheme of the optical fiber side-emitted light, and ease integration ofthe light source into a system. Other embodiments are also described.

BACKGROUND

An optical fiber is known to bring an optical signal from one fiber endto another fiber end without significant losses. In other cases, thefiber is designed to leak the optical signal in a directionsubstantially transverse to the propagation direction of the opticalsignal. This effect is typically the result of the interaction of light(the optical signal) with integrated scattering regions (e.g. holes) inthe fiber. The scattering regions may be realized by adding elementswhile drawing the fiber, or they may be realized through mechanical,laser or chemical post-processing of the fiber.

In other cases, luminescent materials are integrated inside thefiber-core material, inside the cladding, or inside a coating of thefiber, to partially or completely convert the primary or propagatinglight into secondary light that has lower or higher wavelength than theprimary light.

SUMMARY

An embodiment of the invention is an optical fiber side-emitting lightsource that has a side-emitting optical fiber as the light emitter,having a fiber core through which primary light propagates, e.g., inaccordance with total internal reflection off a fiber cladding of theoptical fiber. A lengthwise segment, of a whole length of the fiber,contains a scattering region, which serves to redirect the propagatingprimary light (that is, propagating in the fiber until it enters thesegment) sideways out of the fiber. An active, photoluminescent materialmay also been integrated with the fiber, e.g., as a layer or coating onan outer side surface of the cladding of the fiber, to be stimulated bythe redirected primary light and produce wavelength converted secondarylight. In one embodiment, the secondary light is combined with some ofthe redirected primary light that has been unabsorbed by thephotoluminescent material, resulting in a broader spectrum light, e.g.,white light, emerging sideways from the fiber. Such a combination of theprimary light and secondary light is not limited to the generation ofwhite light however; the photoluminescent material and the primary lightwavelength can be designed to alternatively yield side-emitted light ofanother color, e.g. blue, green, yellow, orange, or red.

The side-emitting fiber, including at least its lengthwise segment,which is the actual light emitter, is also integrated with a compositeovercoating structure having a designed shape (also referred to here asa shaped overcoating structure). The term “composite” is used here todescribe a structure that is made of at least two dissimilar materials,dissimilar in terms of physical or chemical properties, that are joinedtogether such that the characteristics of the resulting combinationstructure is different from those of its individual constituent parts.For instance, the composite structure can be made of a combination ofone or more inactive, light transmissive parts or layers, and areflective part or layer.

The composite overcoating structure may be designed to: beasymmetrically shaped such that it reflects the side-emitted light fromthe fiber in a preferred “asymmetric” manner, e.g. directional or havinga preferred transverse direction, not omnidirectional, such as theredirected light emerging from the overcoating structure through only aportion of the entire circumference of the structure (referred to hereas the top surface or top layer); be asymmetrically shaped or keyed onits outside bottom surface in order to ease its assembly into a system(e.g. by inserting it longitudinally); be made of dissimilar materialsthat are chosen such that it is selectively opaque, transparent orsemi-transparent in an asymmetric way to the side-emitted light emergingfrom the fiber; be made of dissimilar materials that are chosen suchthat it is less flexible than the fiber thereby forming an exoskeleton;be made of dissimilar materials that are chosen such that it isimpermeable or hermetic to the external environment (e.g. waterproof orgas proof); be made of dissimilar materials that comprise additionalinserts in order to ease its assembly into a system; exhibit an outer orinner surface that is mechanically structured such that it redirects theside-emitted light from the fiber in a preferred direction, e.g., aprismatic structure having elongated prism cells that are oriented sideby side, not end to end, forming a sequence of cells in the direction ofthe longitudinal axis of the optical fiber (the longitudinal direction.)

A method for manufacturing the inactive, light transmissive portion ofthe shaped overcoating structure includes a succession of an extrusionprocess where the fiber has been previously formed and is fed through anozzle while being covered by the inactive light transmissive materialin fluid form, that gives a preliminary shape to the light transmissiveportion (once the light transmissive material has solidified afterextrusion), followed with a selective photo- or thermal polymerizationprocess or a mechanical abrasion process to achieve precision in theshaping of the bottom surface of the extruded light transmissiveportion. Another method for manufacturing the shaped, overcoatingstructure may be the succession of an overmolding process, where thefiber is positioned inside a mold that exhibits the counter orcomplementary shape of the final or desired light transmissive portion,combined with a selective photo- or thermal polymerization process toachieve precision in the shaping of the bottom surface of the lighttransmissive portion. In either case, the formation of the lighttransmissive part may be followed with a method for manufacturing thereflective part, on the bottom surface of the light transmissive part,by depositing, sputtering, dipping or evaporating a reflective materialsuch as aluminum onto the bottom surface of the light transmissive part.In another embodiment, instead of a reflective layer, a diffusive layermay be formed on the bottom surface; this may be done by depositing,sputtering or evaporating a mixture of diffusing particles onto thebottom surface, or dipping the light transmissive portion into a mixtureof diffusing particles.

The summary given above does not include an exhaustive list of allaspects of the invention. It is contemplated that the invention mayencompass all systems and methods that can be practiced from allsuitable combinations of the various aspects summarized above, as wellas those disclosed in the Detailed Description below and particularlypointed out in the Claims, and in the associated Drawings. Suchcombinations may have particular advantages that are not recited in theabove summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention are illustrated by way of example andnot by way of limitation in the figures of the accompanying drawings inwhich like references indicate similar elements. It should be noted thatreferences to “an” or “one” embodiment of the invention in thisdisclosure are not necessarily to the same embodiment, and they mean atleast one. Also, in the interest of conciseness and reducing the totalnumber of figures, a given figure may be used to illustrate the featuresof more than one embodiment of the invention, and not all elements inthe figure may be required for a given embodiment.

FIG. 1a is a perspective view of an example of a light source having acomposite overcoating structure.

FIG. 1b shows a parabolic, composite overcoating structure, in a sectionview in a transverse plane.

FIG. 1c is illustrating the side-emitted light emerging from theembedded fiber and redirected by the composite structure of FIG. 1 c.

FIG. 2a shows a section view in a longitudinal plane of a compositeovercoating structure having a prismatic lens top layer.

FIG. 2b illustrates some of the light redirection and recyclingfunctions of the composite structure of FIG. 2 a.

FIG. 2c shows a section view in a transverse plane of the compositestructure of FIG. 2 a.

FIG. 3a shows a section view in a transverse plane of a compositeovercoating structure having a microlens array structure at its topsurface.

FIG. 3b shows a section view in a longitudinal plane of the compositeovercoating structure of FIG. 3 a.

FIG. 4a shows a section view in a transverse plane of a compositeovercoating structure having a single lens structure at its top surface.

FIG. 4b shows a section view in a longitudinal plane of the compositeovercoating structure of FIG. 4 a.

FIG. 5 shows a section view in a transverse plane of a compositeovercoating structure that is integrated with a polygonal bottom part.

FIG. 6 shows a section view in a transverse plane of a compositeovercoating structure that is integrated with a polygonal bottom partthat has one or more knobs embedded therein that extend outward of thebottom part.

DETAILED DESCRIPTION

Several embodiments of the invention with reference to the appendeddrawings are now explained. Whenever the shapes, relative positions andother aspects of the parts described in the embodiments are notexplicitly defined, the scope of the invention is not limited only tothe parts shown, which are meant merely for the purpose of illustration.Also, while numerous details are set forth, it is understood that someembodiments of the invention may be practiced without these details. Inother instances, well-known structures, and techniques have not beenshown in detail so as not to obscure the understanding of thisdescription.

In this disclosure an optical fiber side-emitting light source isdescribed whose overcoating structure is made of dissimilar materialsthat are designed and shaped in order to support the redirection andre-shaping of the light emerging from the side of an optical fiber thatis embedded in the overcoating structure. The light source may be usedas part of any illumination system.

In accordance with an embodiment of the invention and referring now toFIG. 1a , a fiber-based side-emitting light source has an optical fiber6 that may have a core and a cladding. Primary propagating light isproduced by a light emitter such as a laser or a light emitting diode(LED) that is coupled to the fiber (not shown.) The primary lightpropagates along a center longitudinal axis 2 of the fiber 6, in adownstream direction as shown, until it is scattered out of the fiberthrough a side of the fiber 6, by a scattering zone (e.g., formed in acore of the fiber 6.) The scattered radiation or out-coupled light takesplace in a direction substantially transverse to the longitudinal axis 2of the fiber 6, either in a directional manner (forming a cone or lobeof light having a radial span of under 360°) or in an isotropic oromnidirectional manner (radiating at equal strength all around thefiber). Examples of scattering zones that can yield such a result can befound in international patent application no. PCT/IB2012/000617 □(WAVEGUIDE APPARATUS FOR ILLUMINATION SYSTEMS) filed 28 Mar. 2012. Othertypes of side-emitting optical fibers can alternatively be used. Thefiber 6 may also have formed on it a layer of photoluminescent materialto perform wavelength conversion upon the primary propagating light, toresult in a side-emitted light that includes secondary light having adifferent wavelength than the primary light. The resulting side-emittedlight may exhibit a broader spectrum as compared to the primary light,e.g. white light resulting from the combination of unabsorbed primarylight and the secondary light. Alternatively, the photoluminescentmaterial and the wavelength of the primary light may be selected suchthat very little primary light is left unabsorbed, resulting in theside-emitted light emerging from the fiber 6 being dominated by thesecondary light, e.g. red or infrared.

Still referring to FIG. 1a , there is a light transmissive part 3 thatconforms to the side surface of the fiber 6, and a reflective part 4(also referred to as a reflective backing), both forming a single,composite overcoating structure (where the fiber 6 is “embedded” withinthe light transmissive part 3 of the composite overcoating structure.)The light transmissive part 3 may be made of a single, lighttransmissive, inactive (i.e., not photoluminescent, or not wavelengthconverting) material, e.g., polycarbonate, and may completely surroundthe side surface of the fiber 6 and may leave no air gaps between thefiber and the reflective part 4, the latter conforming to the bottomsurface of the light transmissive part 3 (as shown.) All of the lighttransmissive part 3 may be made of the same material, or it may becomposed of layers of different materials.

The overcoating structure of FIG. 1a may alternatively be viewed ashaving a solid body (e.g., the light transmissive part 3) that is madeof an inactive, light transmissive material and is generally cylindrical(having a side surface that extends from a near end or face to a far endor face) but without rotational symmetry about an internal, longitudinalaxis or spine of the body (e.g., the center longitudinal axis 2. Anexternal reflector (e.g., the reflective part 4) has a curved, lightreflective surface that conforms to and abuts a portion of the sidesurface of the solid body while leaving another portion of the solidbody (e.g., the top layer or top surface 7) uncovered for theillumination light to emerge therefrom after being reflected by thelight reflective surface of the reflector.

The overcoating structure serves to shape a specific illumination schemeor pattern of radiation of the side-emitted light, and/or eases theintegration of the light source into a system. It may also serve as anexoskeleton of the light source (where the light transmissive part 3 ismade of a material that is more rigid than the fiber 6.)

FIG. 1b shows several aspects of an example composite overcoatingstructure. This is a section view in a transverse plane (transverse tothe longitudinal axis 2 of the fiber 6), with FIG. 1c illustrating theside-emitted light emerging from the embedded fiber 6. One aspect thatis shown here is that the light transmissive part 3 has a flat orentirely horizontal top layer 7 (or top surface 7), which is not coveredby the reflective part 4 and through which the concentrated orredirected side-emitted light emerges, e.g., into air that surrounds thelight source. This is facilitated by the “asymmetric shape” of thecomposite structure about the center longitudinal axis 2, which refersto the fact that it lacks rotational symmetry about the centerlongitudinal axis 2. However, as best illustrated in FIG. 1c , theovercoating structure may have left-right reflection symmetry across avertical, longitudinal plane 5 (in which the center longitudinal axis 2lies.)

In the particular example of FIGS. 1b-1c , the light transmissive part 3has a “parabolic” shape, and where the reflective part 4 is formed as alayer that covers and conforms to the bottom surface of the lighttransmissive part 3, while the latter's top surface (or top layer) 7 isnot covered, as shown; the light gathering function of the compositelighting structure is however not limited to this shape. Any alternativeshape for the reflective part 4 (and its conforming, bottom surface ofthe light transmissive part 3) that concentrates the light emerging fromthe side of the fiber 6 (e.g., as in FIG. 1b ) in a preferred directionmay be possible, such as a U-shape (see FIG. 1a ), a half or partialcylindrical shape, a half or partial elliptical shape, a hyperbolicalshape, and a multi-segmented shape (composed of straight or curved linesegments, similar or different, and that are joined end to end to form alonger curve.) In one embodiment, the entirety of the outer side surfaceof the light transmissive part 3 (having any one of the above shapes),or its complete side circumference, is divided into two, contiguoussections, namely the top surface or top layer 7, and the rest which isreferred to here as the bottom surface. The bottom surface may be curvedand covered in its entirety by the reflective part 4, but the topsurface is not curved (flat) and is not covered at all by the reflectivepart 4.

The asymmetrical shape of the composite overcoating serves toconcentrate and redirect the side-emitted light (that is emerging fromthe fiber 6) in a preferred outward transverse direction, which in thecase of the examples here is directed outward through the top surface 7(or top layer 7) of the light transmissive part 3. FIG. 1b shows theinteraction of the light that emerges from the side of optical fiber,with the overcoating, in a plane transverse to the longitudinal axis 2of the fiber 6. The longitudinal axis 2 of the optical fiber 6 in thisexample is substantially positioned on a vertical symmetry axis (lyingin the vertical longitudinal plane 5) of the parabolic shape, in thevicinity of the focus of the parabola (that is defined by the bottomsurface). As seen in the perspective view of FIG. 1c , light emergingfrom the lengthwise segment 9 of the fiber 6 is redirected by thereflective part 4 in a transverse direction, and, especially due to theasymmetric shape of the reflective part 4. In one embodiment, theredirected light emerges from the composite structure from only the toplayer or surface 7 of the composite lighting structure (due to theentirety of the bottom surface being covered by the reflective part 4).

FIG. 2a and FIG. 2b show another composite structure in a section viewin a longitudinal plan, but where the top layer 7 is mechanicallystructured into a “prismatic lens” (or simply, prismatic) structure 10(although the light redirection and/or recycling function of themechanical structure is not limited to a prismatic lens—see for exampleFIG. 3a and FIG. 4b . A goal here is to redirect and recycle the lightthat is emerging transversely from the fiber 6 and that reaches the topsurface of the light transmissive part 3, so as to become morecollimated as it emerges outward, and along the length of the fiber 6.The prismatic structure 10 may have any suitable combination ofadjacently placed, prism cells or conical cells, each of which may betilted relative to the vertical, e.g. a one-dimensional array ofadjacently placed, tilted prism cells, or other types of prism cellsthat are arranged to form a prismatic lens that achieves a particularlight beam redirection function. In this embodiment of the prsimaticstructure 10, each individual prism cell is elongated in the transversedirection as seen in FIG. 2c , and the prism cells are positioned ororiented side by side (not end to end) in the longitudinal direction asseen in FIG. 2a and in FIG. 2b . In other embodiments, the prism cellsmay not be elongated, e.g., they may be squares. The prismatic structure10 may be made of a suitable light transmissive material, which may bedifferent than that of the light transmissive part 3 which is joineddirectly below; it may be made as separate piece (of which the topsurface or top layer 7 is a part) that is then joined to a flat topsurface of the light transmissive part 3. FIG. 2b shows the interactionbetween light that emerges from the side of the optical fiber 6 and thecomposite overcoating, in a plan longitudinal to the fiber 6. Lightemerging from the fiber may be directly redirected by refraction at theair-prism interface which is indicated as (1) in the figure, and it mayalso be indirectly redirected, i.e. undergoing several reflectionsinside the composite lighting structure before leaving it, indicated as(2) in the figure. FIG. 2c shows the composite structure of FIG. 2a in asection view in a transverse plane.

FIG. 3a shows a section view in a transverse plane of a compositeovercoating structure having a microlens array structure 12 at its topsurface 7. FIG. 3b shows a section view in a vertical longitudinalplane, of the composite overcoating structure of FIG. 3a . In thisembodiment, each individual microlens is elongated in the transversedirection as seen in FIG. 3a , and the microlenses are positioned ororiented side by side (not end to end) in the longitudinal direction asseen in FIG. 3b . The individual microlenses of the microlens structure12 are said to “selectively” focus or homogenize the side-emitted lightout of the overcoating structure, in contrast to the single continuouslens structure 14 shown in FIG. 4a and in FIG. 4b that “totally” focusesthe side-emitted light out of the overcoating. The microlens arraystructure 12 and the single continuous lens structure 14 may each bemade of a suitable light transmissive material, which may be differentthan that of the light transmissive part 3 which is joined directlybelow; each may be made as separate piece (of which the top surface oftop layer 7 is a part) that is then joined to a flat top surface of thelight transmissive part 3.

FIG. 5 and FIG. 6 show further aspects of an embodiment of the compositestructure, where different examples of a bottom part of the compositestructure are shown that can serve to more easily affix the light sourceas part of a larger system. FIG. 5 shows a polygon shaped or polygonalbottom part 16, which on one side conforms to the outer face of thereflective part 4 while on the opposite side is polygon shaped (here,having a left corner joined by a straight section to a right corner,although other polygonal shapes are possible.) The polygonal shapeenables use of the bottom part 16 as a keyed structure, to fit the lightsource into a mating, keyed receptacle of the system. FIG. 6 shows thecombination of the structure of FIG. 5 and several knobs 17 (two arevisible), where the knobs 17 are affixed to the outer face of thepolygonal bottom part 16 and extend outward therefrom. The knobs 17 canserve to affix the light source to a system. The knobs can be made ofthe same material as the polygonal bottom part 16 such that they form asingle or integral part of the light source. Alternatively, the knobs 17can be separately formed pieces that are bonded to or inserted into thepolygonal bottom part 16, e.g., prior to a polymerization process thatyields the precise boundary of the outside face of the polygonal bottompart 16.

While certain embodiments have been described above and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat the invention is not limited to the specific constructions andarrangements shown and described, since various other modifications mayoccur to those of ordinary skill in the art. For example, while FIGS.2a-2c show the prismatic lens structure composed of elongated prismcells arranged side by side in a sequence that extends in thelongitudinal plane, an alternative may be to orient the prism cells sideby side in a sequence extending in the transverse plane. The descriptionis thus to be regarded as illustrative instead of limiting.

What is claimed is:
 1. A composite structure having an embedded,side-emitting optical fiber, comprising: an optical fiber having alengthwise segment in which a scattering structure is formed that is toredirect primary propagating light within the fiber, and an activephotoluminescent layer integrated in the optical fiber that is towavelength-convert the primary propagating light into secondary light,wherein the secondary light is emitted out of the fiber through an outerside surface of the lengthwise segment of the fiber; and a compositeovercoating formed on the outer side surface through which the secondarylight is emitted out of the lengthwise segment of the fiber, having (i)an inactive light transmissive portion that does not wavelength-convertand is formed on and entirely surrounds the outer side surface throughwhich the secondary light is emitted out of the lengthwise segment ofthe fiber, and has an asymmetric shape about a longitudinal center axisof the fiber, and (ii) a light reflective layer that is formed on andconforms to an outer side surface of the inactive light transmissiveportion except for a top layer thereof, wherein the secondary light, asemitted from the outer side surface of the lengthwise segment of thefiber and then redirected by the reflective layer, is to emerge from thecomposite structure through the top layer.
 2. The composite structure ofclaim 1, wherein a cross section of the light reflective layer, taken ina transverse plane, defines a parabola, and the lengthwise segment ofthe fiber is positioned in the vicinity of the focus of the parabola. 3.The composite structure of claim 1 wherein a cross section of the lightreflective layer, taken in a transverse plane, defines part of a circle,ellipse, or hyperbola.
 4. The composite structure of claim 1 wherein across section of the light reflective layer, taken in a transverseplane, defines a line that includes a plurality of line segments ofdifferent curvatures.
 5. The composite structure of claim 1 wherein across section of the light reflective layer, taken in a transverseplane, defines a line that includes a plurality of straight linesegments joined end to end.
 6. The composite structure of claim 1wherein the top layer of the inactive, light transmissive portioncomprises a plurality of prisms oriented side by side, not end to end,in the direction of the longitudinal axis of the optical fiber.
 7. Thecomposite structure of claim 1 wherein the top layer of the inactive,light transmissive portion comprises a plurality of microlenses in alongitudinal plane or in a transverse plane.
 8. The composite structureof claim 1 wherein the top layer of the inactive, light transmissiveportion comprises a single convex lens in a longitudinal plane or in atransverse plane.
 9. The composite structure of claim 1 wherein thecomposite overcoating further comprises a bottom portion whose one sideconforms to and is in contact with a bottom surface of the lightreflective layer and whose opposite side is polygon shaped in alongitudinal plane or in a transverse plane.
 10. The composite structureof claim 9 further comprising a plurality of knobs that are affixed tothe bottom portion and that protrude therefrom.
 11. The compositestructure of claim 10 wherein the knobs are made of the same material asthe bottom portion of the composite overcoating or are formed as anintegral part of the bottom portion.
 12. The composite structure ofclaim 10 wherein the knobs are formed as separate pieces than the bottomportion, and are bonded to the bottom potion.
 13. The compositestructure of claim 1 further comprising a light emitter that producesthe primary propagating light and is coupled to the optical fiber. 14.The composite structure of claim 13 wherein the light emitter comprisesa laser or a light emitting diode that produces the primary propagatinglight.
 15. The composite structure of claim 1 wherein the lightreflective layer covers a majority of the entire area of the outer sidesurface of the inactive light transmissive portion, and furthercomprising a light emitter that produces the primary propagating lightand is coupled to the optical fiber.
 16. The composite structure ofclaim 15 wherein the light emitter comprises a laser or a light emittingdiode that produces the primary propagating light.
 17. A lightingstructure comprising: a solid body made of an inactive, lighttransmissive material and being generally cylindrical but withoutrotational symmetry about an internal longitudinal axis or spine of thebody, wherein the body has a side surface that extends from a near faceof the body to a far face of the body; an optical fiber having alengthwise segment in which a scattering structure is formed that is toredirect primary propagating light within the fiber, and an activephotoluminescent layer integrated in the optical fiber that is towavelength-convert the primary propagating light into secondary light,wherein the secondary light is emitted out from a side surface of thelengthwise segment of the fiber into the solid body, wherein thelengthwise segment of the fiber is positioned inside the solid body,entirely coinciding with the longitudinal axis of the solid body; and anexternal reflector having a curved, light reflective surface thatconforms to and abuts a portion of the side surface of the solid bodywhile leaving another portion of the solid body uncovered for thesecondary light to emerge therefrom after being reflected by the lightreflective surface of the reflector.
 18. The lighting structure of claim17 wherein a cross section of the external reflector, taken in atransverse plane relative to the longitudinal axis, defines a parabola,and wherein an intersection of the transverse plane and the lengthwisesegment of the fiber is at the focus of the parabola.
 19. The lightingstructure of claim 18 wherein the external reflector covers a majorityof the entire area of the side surface of the solid body.
 20. Thelighting structure of claim 19 wherein said another portion of the solidbody that is uncovered by the external reflector is planar.
 21. Thelighting structure of claim 17 wherein said another portion of the solidbody that is uncovered by the external reflector is generally planarwith a layer of microlenses.
 22. The lighting structure of claim 17wherein said another portion of the solid body that is uncovered by theexternal reflector is generally planar with a layer of prisms throughwhich the secondary light is to emerge redirected.
 23. The lightingstructure of claim 17 wherein the external reflector covers a majorityof the entire area of the side surface of the solid body.
 24. Thelighting structure of claim 17 wherein said another portion of the solidbody that is uncovered by the external reflector is planar.
 25. Thelighting structure of claim 23 further comprising a light emitter thatproduces the primary propagating light and is coupled to the opticalfiber.
 26. The lighting structure of claim 25 wherein the light emittercomprises a laser or a light emitting diode that produces the primarypropagating light.
 27. The lighting structure of claim 17 furthercomprising a light emitter that produces the primary propagating lightand is coupled to the optical fiber.
 28. The lighting structure of claim27 wherein the light emitter comprises a laser or a light emitting diodethat produces the primary propagating light.